Face values

Published: 3-Jan-2007

SPC takes a look at some of the latest colour cosmetic technologies as highlighted at the recent IFSCC congress in Osaka and the SCC conference in New York

SPC takes a look at some of the latest colour cosmetic technologies as highlighted at the recent IFSCC congress in Osaka and the SCC conference in New York

Just in case anybody was in any doubt as to the value of colour cosmetics, LVMH has developed questionnaires to measure the impact of make-up on women's quality of life. As reported at the IFSCC (16-19 October 2006) these have enabled the company to establish specific values in France, Japan and the US. For example: in France make-up is essential for women to be in full harmony with the way they are and perceive themselves; Japanese women are very much aware of the way make-up helps them to gain social and professional credibility; and in the US women are particularly concerned with the way make-up helps them stress their qualities or have more glamorous or natural attitudes. Result clusters were also very revealing. For instance in France younger women paid much more attention to the eyes while more mature women favoured the lips, also accepting a more sexual side to their make-up.

But one area that receives a huge amount of attention by both women and those developing products for them is the complexion. As P&G's Akira Matsubara pointed out in Osaka, translucent skin is considered the ideal and this involves the integration of colour, glow and texture. New methods were established to measure the integration of these parameters and develop technical model for translucency. Here the sensorial perception of skin translucency was translated into measurable numerical descriptions using a dual-polarised imaging system with colour, glow and texture as an index. Translucent skin has a larger colour graduation inside and multi-layered colorimetric structure while dull skin has a more mono-layered structure.

Transparency and glossiness are other words used to express beauty and were the subject of work reported in Osaka by Noriko Nakashima from Kobe. Under investigation was the relationship between the visual evaluation of skin and the intensity of the specular reflection and the diffuse reflection from the skin's surface. A polarised light filter and strobe light were used to establish specular and diffuse reflection. Nakashima said visual factors such as transparency and glossiness correlated with the optical reflection of the skin surface and they were also affected by diffuse and specular reflection respectively. She said the results suggested that some visual factors were simply evaluated by optical factors such as diffuse and specular reflection. Quite a lot of the work reported at the 2006 IFSCC meeting focused on just how to try and optimise the natural surface of the skin through colour technologies.

Keeping up appearances

Various kinds of pearlescent pigments use interference colour phenomena and area used as lustre powders in colour cosmetics and they have increasingly been formulated into based cosmetics in recent years to enhance beauty.

Kao's Eiichiro Misaki and his colleagues aimed to reproduce the natural beauty of a youthful complexion using a multi-angle image capturing system developed to extract quantitative data on the appearance of a human face by taking multiple images. This showed that the chroma of ageing skin decreases rapidly towards the specular region while beautiful skin maintains high chroma even in the specular region. To design a coloured material that provides higher chroma in the specular region an optical simulation method for pearlescent pigments was developed to accurately predict interference colours. The method simulates pigments with multilayered structures, and includes complex refractive indices of the layers, and the real thickness distribution of the substrate. Multilayer pigments were designed with the structure TiO2/Fe2O3/Mica/Fe2O3/TiO2, showing high chroma in the specular region. Pearlescent pigments were produced with the desired properties through the development of a sophisticated nanoscale coating process and the desired pearlescent pigment was obtained, free from the red colour of iron oxide.

Nihon Koken Kogyo synthesized ultrafine and flaky titanium dioxide with interference colour, developing skin colour powder with bright pink interference colour for points of specific reflection and shine. The problems of dull skin and facial slackness were addressed using the powder to achieve visual and psychological improvements. In anti-ageing, adjustments using bright skin colour, lustre and healthy blood colour can be very effective, concluded the company's researchers.

The colouring of the reflection of pearlescent pigments is attributed to additive mixture of interfering light and Kao obtained a brightly coloured foundation film by mixing a sufficient amount of medium-sized pearlescent pigments into foundations. Five foundation films, containing pearlescent pigments with different glossy colours were prepared and gonio-spectrophotometry was used to determine the angle dependence of the reflected spectra and establish the approximate optical characteristics of the films. Computer graphic images of faces with foundation applied were prepared. These were evaluated visually and showed colour differences in skin impressions, aiding the development of a foundation to control such facial impressions.

South Korea's Pacific Corp reported on a new interference colourant composed without any organic dye or lake. It is composed of alumina coated with titanium dioxide and is used to achieve a wrinkle shading effect.

Shiseido turned to the properties of photocopy toners to develop an ultra hyper chromatic foundation. It has been considered too hard for foundations to give skin a translucent finish due to volume of pigment but recent advances in computer graphic technology suggest subsurface light transport. Shiseido felt titanium dioxide and iron oxide, the typical pigments affecting the properties of light transport on skin, had not been studied carefully enough. Shiseido developed a cosmetic toners, from red and yellow toners, with practically no light absorption at 600-700nm and a new colour system for a foundation of which colour is expressed as higher chroma values was created. The hyper-chromatic foundation based on the new colour system was found to be superior to its conventional counterpart in terms of producing a translucent and soft skin appearance.

Shiseido also reported the development of a hybrid powder based on a computer simulation (Finite Differential Time Domain) and its application to base make-up products. An ideal hybrid powder was synthesized based on the optical model with the use of a proprietary shape regulation coating technology in which flaky substrates are coated with microspherical forms of barium sulphate crystals. The resulting hybrid powder is said to exhibit optical characteristics that show a significant diffusion characteristic in the visible light region. The foundation mixed with this powder is said to conceal pores, small wrinkles, freckles and age spots and provide a fine, smooth texture thanks to microscopic reflection characteristics never before achieved.

Multi-refraction rather than interference was the inspiration for the novel optically anisotropic controlled powder developed by Kaito Kasei Kogyo and the material shows significant change in chromatic level rather than a change in hue value. An inner core is the hemispherical-shaped powder that shows an ability of light transparence or translucence and the outer shell is translucent organic dye.

Lips & eyes in focus

Dow Corning has produced some interesting silicone acrylate copolymers specifically for application in colour cosmetics, highlighted at both the Japan and the US meetings. They are said to offer enhanced options for durable, long-lasting film formers with good sensory properties. These film formers have a distinctive structure based on a polyacrylate backbone and dendritic silicone side chains. Specifically, acrylates/polytrimethylsiloxymethacrylate copolymer is said to offer resistance in foundations, sebum absorption and long-lasting and comfortable lipstick.

To assess lipstick smoothness, Amorepacific Corp of South Korea introduced the novel concept of frictional force, substituted for smoothness properties, measurable by rheometer and therefore producing objective numerical data. This was highly correlated with sensory tests. On the basis of the new measurement system, factors related to smoothness were ordered by effect, oil viscosities being the most important; the lower the viscosity the less the frictional force. Low melting point waxes and powder substances are next in importance; generally spherical powder is superior to plate-shaped. Amorepacific is now focusing on developing lipstick formulas with a reduced frictional force. Assessment of moisturisation, pearl gloss and temporary wrinkle-covering power using conductance, TEWL and digital imaging of lips before and after lipstick application was the focus of another South Korean company, Enprani. The lipstick formulations tested incorporated photoprotection and titanated pearl.

The trend towards natural is reaching all areas, including colour cosmetics. After screening a wide range of botanical waxes using crystallographic studies Nippon concluded that rice bran wax the most suitable for a stable lipstick with a botanical positioning.

Ciba was promoting its new Calisha pigments for colour cosmetics at the December's SCC meeting. The company says many of the pigments within the collection provide easy compressibility, low oil absorption, high colour loads, intrinsic skin affinity, enhanced deposition and durability of the colour on the skin as well as low dusting for better production hygiene. More information on these will be available soon.

South Korea's Hanbul Cosmetics described the application of the principle of sol-gel transition of alginic acid to mascara in a poster presented at the IFSCC meeting. Alginic acid is a linear polysaccharide composed of a cell wall and an intercellular cementing matrix of brown algae and is used as a viscosity increasing agent, stabilizer, thickener and emulsifier in cosmetics, pharmaceuticals and food. In Hanbul's work, Na-alginate was used in an o/w black mascara and calcium chloride was formulated into a transparent topcoat and these were spread onto the lashes alternately. The outcome was said to be excellent volume, waterproofing, tackiness and speed results. Coty says that while much work has been published on the rheological properties of mascara there is little available on the influence of shear on structural changes. Work reported in Osaka addressed this, visualising structural changes in mascara texture related to shear using conventional laboratory equipment. This kind of visualisation is said to improve the understanding of textural and rheological properties and therefore polymer selection depending on pigment combinations within the same mascara system.

There comes a time in the evening when if the skin is to be maintained in optimum condition all this colour needs to be removed effectively. Unilever has this covered with a new make-up remover with high make-up removability and high mildness, again reported in Osaka. A combination of a high level of non-ionic surfactants and humectants was said to provide a balanced system delivering both parameters and this was confirmed both in vitro as well as in clinical and consumer evaluation. Good shear thinning was said to be related to the sensorial cue of rapid dissolution (seeping) of make-up into the product and this was positively correlated to consumer perception of make-up removal performance.

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